Creatine phosphokinase isoenzymes and the diagnosis of myocardial infarction.

Although CPK-MB determinations are useful adjuncts in diagnosing myocardial infarction (MI), the values are frequently elevated in circumstances other than infarction and almost certainly remain normal in some patients who have sustained myocardial necrosis. Elevations in patients with trauma, sustained tachyarrhythmias, and unstable angina can be particularly confusing. As there is still no adequate diagnostic standard for MI, in many cases the clinician can only make a judgment as to the probability of infarction.